On in vitro Precipitation of Bile

Abstract

Precipitation of bile on in vitro incubation was studied with special reference to the difference between the calcium bilirubinate stone and the cholesterol stone cases. In the case of calcium bilirubinate stones, bile was mostly infected and invariably yielded on incubation a precipitate which consisted mainly of spherical particles of calcium bilirubinate and resembled in composition a calcium bilirubinate stone. After incubation, the content of bilirubin decreased and that of free glucuronic acid increased in bile, and it was found that bilirubin glucuronide in bile was hydrolyzed by the activity of β-glucuronidase of bacterial origin into free bilirubin and free glucuronic acid and the former combined with inorganic elements to form insoluble bilirubinates. This type of precipitation is found to represent the initial stage of formation of calcium bilirubinate stones. The bile of cases with cholesterol stones, on the other hand, occasionally produced precipitates even in non-infected specimens. Moreover, the precipitate, containing many cholesterol crystals, was different in composition from that of bile in calcium bilirubinate stone cases. From these and other findings it was presumed that the precipitation of bile in cholesterol stone cases might occur by a different mechanism.